| 摘要 |
A system is provided for determining an eccentricity vector epsi which defines the magnitude and direction of an initial placement displaced from a desired location of a centroid O of a right quadrilateral semiconductor wafer which may be clear or opaque. With an initial point of reference desirably established on its peripheral edge for detection by an edge sensor, the wafer is rotated about a point P and a curve defining the profile of the peripheral edge is obtained. The eccentricity vector is computed from the sensed positions of the corners of the wafer and has a magnitude representative of the spatial dislocation of the centroid O relative to the point P and having an orientation phi representative of the angle subtended by a first line connecting the point P and the centroid O relative to a second line connecting opposite corners of the wafer. As processing proceeds, the wafer is inserted into an aligner station, then repositioned from an initial position to a desired position, then advanced seriatim into a plurality of processing stations while maintaining the desired position previously attained. The aligner and the processing stations may be evacuated. The wafer may be post positioned to a new desired position by rotating the wafer until a side thereof is generally parallel to an internal wall of the aligner station, enabling an end effector of a robot arm to readily lift the wafer from its support and advance it into the processing stations while maintaining the desired position previously attained.
|
